A portable terminal apparatus such as a portable terminal device typically includes a first housing having keys such as ten-keys arranged thereon, and a second housing having a liquid crystal display device arranged thereon, the second housing being configured to open and close relative to the first housing. Typical structures for opening and closing the second housing relative to the first housing include a collapsible type structure that opens and closes by connecting the first and the second housings with a hinge mechanism and rotating the second housing relative to the first housing, and a slidable type structure that opens and closes by sliding the second housing relative to the first housing.
In recent years and continuing, portable terminal devices are being provided with more functions, devices capable of receiving digital terrestrial broadcast are being developed, and liquid crystal display devices of such portable terminal devices are being enlarged. As the functions of the portable terminal devices increase, more keys are arranged on a keyboard for performing input processes on the portable terminal devices so that the size of the keyboard tends to become larger. On the other hand, improved portability of the portable terminal device is desired so that there is a limit to increasing the size of the liquid crystal display device or the keyboard.
When the collapsible type portable terminal device is in a collapsed state, its liquid crystal display device is hidden. In this case, the liquid crystal display device cannot be used. Although the slidable type portable terminal device does not have the problem of the collapsible type portable terminal, the first housing and the second housing inevitably overlap when the portable terminal is opened so that space may not be efficiently utilized.
Accordingly, an opening and closing device is disclosed that has a first housing and a second housing that become flat (coplanar) when the first and the second housings are opened (see Patent Documents 1-3). With this configuration, the liquid crystal display device can be used even when the first and second housings are closed. Further, when the first and second housings are opened, there would be no overlapped portion between the first and second housings so that space may be efficiently utilized.